Torrenting also isn't illegal by itself or a direct link to pirating, it is just a very common way of sharing pirated data.
Emulating also isn't illegal by itself of a direct link to pirating, it is just a very common way of playing pirated games.
Just as you can go to to arch linux' web page and download through their recommended method (torrent), you can go play old PS1 games on the PSClassic (based on the PCSX emulator), or play GB/GBC games on your 3DS Virtual Console (in house nintendo-made emulator afaik, correct me if I'm wrong).
I was making fun of that comment to point out the same is true of emulation. However I obviously misinterpreted the initial comment since you're clearly aware emulation itself is legal. Sorry.
2. This way you can buy physical copies of games, keeping full control and the ability to resell them, while also carrying your current game library on an SD card.
Edit: I forgot modding! That's a huge use of emulation.